I started a web page dedicated for 2 way interfacing with the Arduino USB boards and a Macinotosh Computer. With a little bit of modification to the code I believe you can even interface multiple Arduino boards connected to one computer at a time. The link is below.

that's cool. don't know what to do with it yet, but surely a nice direction to go. i did some cocoa programming about 2 years ago, didn't have arduino back then, so the only useful thing that came to my mind was a fullscreen media-centre like application. i stopped working on it when the first "frontrow" rumors started on the web :-/ ...and when i noticed how complex it would get if i made it customisable with applescripts. which was the main idea.

No problem! I really should be calling this a totorial of how to use Xcode with the arduino. I want to become what i call somwhat of an expert if possible at this and writing test programs have always been the easiest way for me to do this so I hope my trials and errors help everyone on here that want to program on a Mac and maybe this will help people that are scared of Xcode. It really is a decent free c++ programing environment. My biggest problem is debugging and I dont like apple's debugger much. I'm glad to help and as I get more spare time i'll post more tutorials.